The combined effect of phase change material (PCM) and fluid flow on the thermal efficiency of solar thermal storage was experimentally investigated in this study in order to determine the appropriate operating conditions. Moreover, a sensitivity analysis was employed to evaluate the greatest effect on thermal efficiency. In the experiments, the effect of PCM weight was tested with three values of 4, 6, and 8 kg. The effect of fluid flow rate was also examined with three values of 2.4, 4.8, and 7.2 L/min. From the experiment, PCM and fluid flow had a significant effect on thermal efficiency. In the case of optimal conditions, the PCM of 6 kg and flow rate of 4.8 L/min provided the water and air heating efficiencies of 65% and 45%, respectively. From the sensitivity analysis, PCM showed the greatest effect on thermal efficiency, leading to a priority factor for solar thermal storage design.
